I’ve been playing with PHP (fun) and google maps (more fun) and my daughter (most fun of all). The results, can be found here: http://www.braindelay.com/baby/outside/. Enjoy, and please feel free to contribute: the more places we get the better it becomes.
If you like this: the source is available here, feel free to play with it (some of it is third party).
UPDATE: I’ve had some trouble getting people to use this because, well, it was hard to use; so I changed it about a little: now it uses MySQL rather than XML to store the locations, and there’s a new, web-based, method for creating new locations.
I’ve also made this available as a mobile service: just point your mobile phone at http://braindelay.com/mobile.